Effect of after‐cooking darkening inhibitors on stability of frying oil and quality of french fries

The effect of two after‐cooking darkening inhibitors, sodium acid pyrophosphate (SAPP) and calcium acetate (CaAc), and their combined effect on frying oil stability and quality of french fries produced were evaluated over a period of 72 h. Samples of frying oil and par‐fried french fries were taken at 3‐h intervals through each experiment and analyzed for selected chemical and physical parameters. As the frying time increased, all the oil samples contained increased amounts of deterioration products. The color index and free fatty acid (FFA) values were highly correlated with frying time. There were no significant effects on oil properties in terms of FFA until 9 h of frying among the 4 pretreatments. However, from 12 to 72 h of frying, oil used to fry potatoes treated with SAPP contained less FFA than oils exposed to CaAc alone or in combination with SAPP. The fat content of par‐fried french fries was approximately 0.11 g/g dry matter and remained relatively constant during extended frying. After‐cooking darkening of par‐fried french fries and final color of the fries were affected by the pretreatment, but not by the frying time.